Control lever devices for a working system and a traveling system are provided in the vicinity of an operator's seat in a construction machine such as a hydraulic excavator or the like in general. A gate lock lever manually tilted/operated at an engine start or when an operator gets on/off the operator's seat is provided on an entrance/exit side of the operator's seat. This gate lock lever is a safety device for preventing unintentional operation of an actuator of a working device and a traveling device. In this case, a gate lock switch is switched to open/close by a tilting operation of the gate lock lever, and it is configured to control operation and stop of the entire hydraulic circuit by the gate lock switch (Patent Document 1). In another example, the one in which safety is further improved by providing another unlock switch in addition to the gate lock lever is known (Patent Document 2).